On Oct. 23, a German research satellite re-entered the earth's atmosphere and plunged into the northeast Indian Ocean's Bay of Bengal.
This event came less than two months after a report, conducted by the National Research Council and sponsored by NASA, warned that the amount of "space junk" orbiting Earth has reached a tipping point.
Donald Kessler, chair of the committee that published the report and former head of NASA's orbital debris research program, has been warning of the risks of space junk since 1978. We asked him about the ins and outs of orbital debris: how much is out there, what does it look like, what happens when these objects collide and what danger do they pose for future space travel and for us on Earth?
Kessler also discusses a troubling scenario he has predicted, which has since been dubbed the "Kessler syndrome." It describes a situation in which cascades of collisions among objects in low-Earth orbit build up debris, making space travel increasingly difficult.
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